A head-mounted display, a head-up display, and a wearable display of glasses type are display apparatuses that, based on an extended optical system applied with a virtual image, display a video image in the very vicinity of the eyeball of a user. Especially, a head-mounted display employs an optical lens high in curvature in order to display a video image having a wide viewing angle in front of the eyes of a user, thereby providing a configuration in which a user looks at a display panel through the lens, while pursuing the reduction in size and weight.